JP5303168B2 - Small wind power system interconnection device - Google Patents

Description

  The present invention relates to a small wind power generation system interconnection device that links a small wind power generation system to a solar power generation system.

  In recent years, surplus power from wind power generation has been purchased by each electric power company after solar power generation, and the groundwork for promoting grid connection of small wind power generation has finally been established. However, since the small wind power generation power is small and the power generation is intermittent, the grid-connected inverter for small wind power generation is not yet commercially available for the reason that the usage rate of equipment is remarkably lowered. For this reason, various grid interconnection technologies for small wind power generators using grid interconnection inverters for photovoltaic power generation have been proposed, but these technologies have many problems and have not yet been put into practical use. In the technique of Patent Document 1, a device for boosting the voltage of the wind power generation battery to the solar voltage is required. As a result, there is a problem that the apparatus becomes large and loss occurs in the process of boosting. From the above background, it was actually impossible to connect the grid of small wind power generation.

Japanese Patent No. 3966998

  In view of the above problems, an object of the present invention is to provide a small wind power generation system interconnection device that can be connected to a solar power generation system with a simple configuration.

In order to solve the above-described problem, a small wind power generation system interconnection device according to the invention of claim 1 converts a small wind power generation system from DC power generated by another DC power generation system to AC power having a predetermined frequency. A small wind power generation system interconnection device linked to the AC power system, together with the other DC power generation system via a grid interconnection inverter, and an input terminal connected to the positive electrode of the small wind power generation system, When the input-side ground terminal connected to the negative electrode of the small wind power generation system and the positive electrode of the other DC power generation system are connected to the positive input terminal of the grid-connected inverter, the other DC power generation system While connected to the negative electrode, when the positive electrode of the other DC power generation system is not connected to the positive input terminal of the grid-connected inverter, it is connected to the positive input terminal of the grid-connected inverter When the negative terminal of the other DC power generation system is connected to the negative input terminal of the grid-connected inverter, the other DC power generation is connected to the positive terminal of the other DC power generation system. When the negative pole of the grid is not connected to the negative pole input terminal of the grid interconnection inverter, the output side ground terminal connected to the negative pole input terminal of the grid interconnection inverter, and the small wind power generation system is connected to the other DC power generation system And one of the connected states of the wind power generation connected to the AC power system or the wind power non-connected state connected to the AC power system only the other DC power generation system. Switching means for switching to the switching means, and switching control means for controlling the switching operation of the switching means, wherein the switching control means charges the power storage means for storing wind power generated by the small wind power generation system. Detecting the conducting state based on the charge-discharge state is detected, the wind power interconnection state, or be capable of switching to either one of the wind power non interconnection state, said switching control means, the voltage of the accumulator unit Is detected as charging / discharging state information, and the charging / discharging state is determined by detecting that the voltage detected by the voltage detecting circuit rises or falls to a preset threshold voltage. Composed.

A small wind power grid interconnection device according to the invention of claim 2
The switching means is
A rectifying element that is connected between the output terminal and the output-side ground terminal and that conducts when the wind power generation is not connected,
A switching element connected between the input terminal and the output terminal, and when the switching control means is in a wind power generation linked state, the switching element is switched to a closed state, while the wind power generation non-linked In the case of a state, the switching element is configured to be switched to an open state.

  In the small wind power grid interconnection device according to the invention of claim 3, the switching means includes a first switching element connected between the output terminal and the output-side ground terminal, the input terminal, and the output terminal. A second switching element connected between the first switching element and the second switching element in a closed state when the switching control means is in a wind power generation interconnected state. On the other hand, when the wind power generation is not connected, the first switching element is switched to the closed state, and the second switching element is switched to the open state.

  According to the invention of claim 1, the configuration can be simplified, and the small wind power generation system can be connected to the solar power generation system at a small size, light weight and low cost.

  According to the second aspect of the present invention, only the switching element needs to be controlled, so that the control power can be reduced. In addition, when a photovoltaic power generation system is used as another DC power generation system, a configuration in which the current of the solar cell is not interrupted is possible, and in this case, the operation state of the grid interconnection inverter is adversely affected. There is nothing.

  According to invention of Claim 3, the loss at the time of connecting can be made small. Moreover, the grid connection which suppressed the loss of wind power generation power is realizable. In addition, when a photovoltaic power generation system is used as another DC power generation system, a configuration in which the current of the solar cell is not interrupted is possible, and in this case, the operation state of the grid interconnection inverter is adversely affected. There is nothing.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 is a circuit diagram for explaining a basic configuration and an external connection state of a small wind power generation system interconnection device (hereinafter, interconnection device) of the present invention. This interconnection device 1 is a grid interconnection inverter that converts a DC power generated by a solar cell PV that constitutes a photovoltaic power generation system using a small wind power generation system WG as another DC power generation system to AC power of a predetermined frequency. It is configured to be connected to the commercial power supply system AC together with the photovoltaic power generation system via the INV. The load RL is supplied with power from the grid interconnection inverter INV and the commercial power supply system AC. The small wind power generation system WG is configured to convert the three-phase AC generated power generated by the small wind power generator into predetermined DC power by a rectifier circuit such as a full-wave rectifier circuit and output the same.

  The interconnection device 1 is a wind power generation state in which the small wind power generation system WG is connected to the commercial power supply system AC together with the solar power generation system, or wind power in which only the solar power generation system is connected to the commercial power supply system AC. Among the power generation non-linkage states, the switch unit 2 is switched to one link state, and the switch control unit 3 is configured to control the switching operation of the switch unit 2.

  In addition, the interconnection device 1 includes an input terminal T1 connected to the positive electrode of the small wind power generation system WG, an input-side ground terminal T2 connected to the negative electrode of the small wind power generation system WG, and the positive electrode of the solar cell PV. When connected to the positive input terminal P of the inverter INV, the output terminal T3 connected to the negative electrode of the solar cell PV and the output side ground terminal T4 directly connected to the negative input terminal N of the grid interconnection inverter INV. I have.

  The switching means 2 includes a contact relay S1 as a first switching element connected between the output terminal T3 and the output side ground terminal T4, and a second switching element connected between the input terminal T1 and the output terminal T3. The contact relay S2 is configured. Further, the switching control means 3 switches the contact relay S1 to the open state and the contact relay S2 to the closed state in the wind power generation interconnected state, while the contact relay S1 in the wind power generation unconnected state. Are closed and the contact relay S2 is switched to the open state.

  In FIG. 1, the output of the small wind power generator WG is connected to the battery BT which is a storage means (charging wiring), and the positive and negative outputs of the battery BT are connected to the input terminal T1 and the input-side ground terminal T2 of the interconnection device 1. Connect to each (wiring for discharge). Further, the negative electrode of the solar cell PV is connected to the output terminal T3 of the interconnection device 1, and the negative input terminal N of the grid interconnection inverter INV is connected to the output-side ground terminal T4 of the interconnection device 1. The positive electrode of the solar cell PV is connected to the positive input terminal P of the grid interconnection inverter INV. The output terminals R and T of the grid interconnection inverter INV are connected to the AC load RL and the commercial power supply system AC.

  The contact relay S1 is connected between the output terminal T3 and the output side ground terminal T4 of the interconnection device 1, the contact relay S2 is connected between the input terminal T1 and the output terminal T3, and the input side ground terminal T2 and the output side ground. Terminal T4 is short-circuited.

  In this interconnection device 1, while the battery BT is insufficiently charged (when wind power generation is not connected), the contact relay S1 is closed and the contact relay S2 is opened, and only the generated power of the solar cell PV is connected to the grid. To go. When the charging of the battery BT is completed (at the start of wind power grid connection), the contact relay S1 is opened, the contact relay S2 is closed, and the solar cell PV and the battery BT are connected in series. Since the battery BT has a low voltage (12V or 24V), grid connection operation is not performed at night, and the battery BT is discharged only during the day when the solar cell PV generates power. Is done. Since the solar cell PV can be regarded as a constant current source, a current equal to the output current of the solar cell PV is discharged from the battery BT. This means that wind power is injected into the grid interconnection inverter INV using the power of the solar cell PV. When the discharge of the battery BT is completed (at the end of wind power grid connection), the contact relay S2 is opened and then the contact relay S1 is closed to switch to the grid interconnection of only the solar cells PV.

  These switching operations can be performed at any time by the switching control means 3 based on the charging / discharging state of the battery BT regardless of the power generation state of the solar cell PV and the operating state of the grid interconnection inverter INV. The determination of the charge / discharge state is based on using the voltage detection circuit 4 that detects the voltage of the battery BT as the charge / discharge state information and detects that the detected voltage rises or falls to a preset voltage (threshold). The power source for operation drive such as the voltage detection circuit 4 and the contact relay is obtained from the battery BT.

  In FIG. 1, S1 and S2 are contact relays, but other switching elements such as power MOSFETs and IGBTs may be used. Since the contact relay may cause contact deterioration or welding due to an arc generated when a DC current is opened and closed, it is obvious that a switching element is more suitable in terms of reliability.

  When performing solar power generation and wind power generation in ordinary households, the power generation amount of solar power generation is considerably larger than the power generation amount of wind power generation. Is assumed to be an independent operation of photovoltaic power generation. For this reason, this interconnection device 1 must minimize the adverse effect of solar power generation during single operation, that is, loss when the current of the solar cell PV flows through this interconnection device 1. Also, it must be avoided to affect the operation state of the grid interconnection inverter INV at the time of connection switching. In the configuration of FIG. 1, since the current at the time of connection switching is cut off, there is a possibility that the grid interconnection inverter INV malfunctions due to operation stop of the grid interconnection inverter INV or generation of surge voltage, and countermeasures are necessary. In the hybrid interconnection operation state after connection switching, the voltage (12V or 24V) of the battery BT is lower than the voltage (100V to 350V) of the solar battery PV, so that the grid interconnection such as maximum power point tracking control is performed. The operation of the inverter INV is not affected.

  Next, FIG. 2 shows the present invention in which the contact relay S1 of FIG. 1 is a diode D1 that is a rectifying element that conducts when the wind power generation is not connected, and the contact relay S2 is a power MOSFET (Q2) that is a switching element. It is a circuit diagram which shows other embodiment. Q2 is turned off (open state) when wind power generation is disconnected. For this reason, the diode D1 is turned on and becomes conductive, and the current of the solar battery PV is input to the grid interconnection inverter INV via the diode D1. Q2 is turned on (closed) at the start of wind power integration. Since the reverse voltage by the battery BT is applied to the diode D1, the diode D1 is turned off, and the generated current of the solar battery PV flows through the batteries BT and Q2, and the wind power generated along with the solar power is connected to the system. Input to the interconnected inverter INV. At the end of wind power interconnection, Q2 is turned off, and the current of the solar cell PV is input to the grid interconnection inverter INV via the diode D1.

  In this configuration, only Q2 is switched and the configuration is simplified. Further, since Q2 is connected between the diode D1 and the battery BT, the voltage applied to Q2 becomes the voltage of the battery BT, and a power MOSFET having a low rated voltage can be used. Since the power MOSFET with a low rated voltage has a low on-resistance, the loss of Q2 can be reduced. Moreover, since the interruption | blocking of the electric current of the solar cell PV does not generate | occur | produce, it does not affect the driving | running state of the grid connection inverter INV. However, since the current of the solar cell PV flows through the diode D1 when only the solar cell PV is used, the loss at the diode D1 increases when the amount of power generation is large (about 20 W in the 4 kW system).

  Next, FIG. 3 is a circuit diagram showing another embodiment of the present invention that substantially eliminates the loss of the diode D1 of FIG. S1 and S2 in FIG. 1 are power MOSFETs (Q1 and Q2), respectively. When wind power is not connected, Q1 is turned on and Q2 is turned off. For this reason, the generated current of the solar cell PV flows through the channel portion of Q1 and is input to the grid interconnection inverter INV. Since the applied voltage of Q1 also becomes the voltage of the battery BT, a power MOSFET having a low rated voltage, that is, a low on-resistance can be used. For this reason, the loss of Q1 in this state can be remarkably reduced as compared with the configuration of FIG. In this configuration, Q1 is turned off (Q1 body diode is turned on) at the start of wind power interconnection, Q2 is turned on (Q1 body diode is turned off), and Q2 is turned off (Q1 is turned off) at the end of wind power interconnection. Since Q1 is turned on after the body diode is turned on (the body diode of Q1 is turned off), the current interruption of the solar cell PV does not occur, so that the operating state of the grid interconnection inverter INV is not affected.

  FIG. 4 is a circuit diagram showing another embodiment of the present invention that further reduces the loss of the diode D1 of FIG. S1 in FIG. 1 is constituted by a parallel connection of a contact relay X1 and a diode D1, and S2 in FIG. 1 is a power MOSFET (Q2). When wind power generation is disconnected, X1 is closed and Q2 is turned off. For this reason, the generated current of the solar cell PV flows through X1 and is input to the grid interconnection inverter INV. For this reason, the loss of X1 in this state becomes almost zero. In this configuration, X1 is opened (D1 is on) at the start of wind power grid connection, Q2 is turned on (D1 off), and Q2 is off (D1 is on) at the end of wind power grid connection, X1 is closed ( D1 is off), so that the current interruption of the solar cell PV does not occur, and thus does not affect the operating state of the grid interconnection inverter INV. In addition, since D1 is connected in parallel with X1 and a current bypass circuit is secured, generation of an arc at the time of opening and closing X1 can be suppressed, so that a highly reliable device can be obtained. Further, by using X1 as a latching relay, only the driving power for opening and closing X1 is required, and the control power can be reduced to the same level as in the configuration of FIG.

In addition, this invention is not limited to the said embodiment, It is also possible to change suitably the shape and structure of each part in the range which does not deviate from the meaning of this invention.
(1) The other DC power generation system is not limited to the solar power generation system, but may be any one that outputs DC power as long as it is DC-converted at the output stage of another AC power generation system or a fuel cell power generation system. good.
(2) The switching control means is not limited to the battery voltage, and if it is based on the charge / discharge state, it detects the current (charged amount) and switches according to the determination result of the charge / discharge state, such as completion of charge / discharge. Also good.
(3) As shown in the schematic circuit diagram of FIG. 5A corresponding to FIGS. 1 and 2, the interconnection device 1 connects the output terminal T3 to the negative electrode of the solar cell PV1, and connects the output-side ground terminal T4 to the system. As shown in FIG. 5B, the output terminal T3 is directly connected to the positive input terminal of the grid-connected inverter INV, and the output-side ground terminal T4 is not limited to the configuration directly connected to the negative input terminal N of the grid-connected inverter INV. And a configuration in which the output terminal T3 is connected to the negative electrode of the solar cell PV1 and the output-side ground terminal T4 is connected to the positive electrode of the solar cell PV2, as shown in FIG. You can also In these cases, the same effects as those in FIGS. 1 to 4 can be obtained.

It is a circuit diagram showing one embodiment of the present invention. It is a circuit diagram which shows other embodiment of this invention. It is a circuit diagram which shows other embodiment of this invention. It is a circuit diagram which shows other embodiment of this invention. (A)-(c) which shows other embodiment of this invention is a schematic circuit diagram.

Explanation of symbols

  1 ・ ・ Small wind power generation system interconnection device (interconnection device) 2 ・ ・ Switching means 3 ・ ・ Switch control means 4 ・ ・ Voltage detection circuit, WG ・ ・ Small wind power generation system, BT ・ ・ Battery, PV , PV1, PV2 ... solar cells, INV ... grid-connected inverter, RL ... load, AC ... commercial power supply system, D1 / ... rectifier, S1 / ... first switching element, S2 / ... second switching element , Q1, Q2 ... Power MOSFET, X1 ... Contact relay.

Claims (3)

A small wind power generation system is connected to an AC power system together with the other DC power generation system via a system-connected inverter that converts DC power generated by another DC power generation system into AC power of a predetermined frequency. A small wind power grid interconnection device,
An input terminal connected to a positive electrode of the small wind power generation system;
An input-side ground terminal connected to the negative electrode of the small wind power generation system;
When the positive electrode of the other DC power generation system is connected to the positive input terminal of the grid interconnection inverter, the positive electrode of the other DC power generation system is connected to the negative electrode of the other DC power generation system. When not connected to the positive input terminal of the grid interconnection inverter, the output terminal connected to the positive input terminal of the grid interconnection inverter;
When the negative electrode of the other DC power generation system is connected to the negative input terminal of the grid interconnection inverter, the negative electrode of the other DC power generation system is connected to the positive electrode of the other DC power generation system. When not connected to the negative input terminal of the grid interconnection inverter, the output side ground terminal connected to the negative input terminal of the grid interconnection inverter,
Wind power generation state in which the small wind power generation system is connected to the AC power system together with the other DC power generation system, or wind power in which only the other DC power generation system is connected to the AC power system Switching means for switching to one of the power generation non-connected states,
Switching control means for controlling the switching operation of the switching means,
The switching control means includes
The charge / discharge state of the power storage means for storing the wind power generated by the small wind power generation system is detected, and based on the detected charge / discharge state, either the wind power generation linked state or the wind power generation non-linked state is set. It is capable of switching,
The switching control means includes a voltage detection circuit that detects the voltage of the power storage means as charge / discharge state information, and detects that the voltage detected by the voltage detection circuit rises or falls to a preset threshold voltage. Then, the charge / discharge state is determined . The switching means is
A rectifying element that is connected between the output terminal and the output-side ground terminal and that conducts when the wind power generation is not connected,
A switching element connected between the input terminal and the output terminal,
The switching control means includes
In the case of wind power interconnection state, while switching the switching element to the closed state,
In the case of a wind power generation unconnected state, the switching element is switched to an open state.
The small wind power generation system interconnection device according to claim 1. The switching means is
A first switching element connected between the output terminal and the output-side ground terminal;
A second switching element connected between the input terminal and the output terminal,
The switching control means includes
In the case of a wind power generation interconnection state, while switching the first switching element to an open state and the second switching element to a closed state,
In the case of a wind power generation unconnected state, the first switching element is switched to a closed state, and the second switching element is switched to an open state.
The small wind power generation system interconnection device according to claim 1.

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